1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a self-configurable paging system for a cellular telecommunications network that automatically adjusts the size of a paging area on a per-cell basis.
2. Description of Related Art
Locating mobile stations (MSs) in a cellular telecommunications network is a critical function for the delivery of telecommunications services. The paging operation utilized, however, is a time-intensive and resource-intensive operation. For this reason, many methodologies have been developed over the years in an attempt to reduce the amount of time and resources required for the paging function. For example, instead of paging for an MS in every cell across an entire network, prior art solutions have defined staged paging methodologies in which the paging is done in stages. Smaller areas are defined where a paging attempt is first made, and then progressively wider areas are paged until the MS responds, or the page attempt fails. In a typical paging scenario, an MS may first be paged in a Location Area (LA) which is a group of cells related to the last cell in which the MS was registered. If the MS is not found, the search area is widened to a Paging Area (PA) which is a group of LAs. Finally, if the MS is not found in the PA, a network-wide page attempt may be performed in an area know as a System Area (SA).
In current networks, MSs may typically perform periodic registrations with the network every 10-15 minutes, although this time period may be considerably longer in some areas. MSs also register whenever they move from one LA to another. At registration, the identity of the cell (CellID) where the MS is located is converted into an LA. The LA is then temporarily stored in the Visitor Location Register (VLR) in the currently serving Mobile Switching Center (MSC) in case the MS needs to be located. When the MS needs to be located for delivery of a terminating call, Short Message Service (SMS) message, etc., current systems initially page for the MS simultaneously in all of the cells in the LA where the last registration was performed.
One problem with this existing solution is that the smallest area in which the subscriber is paged, the LA, may still represent a sizeable area, and may still require a large amount of system resources for the first page attempt. Some LAs, for example, can contain several hundred cells. Since the MS can only be in one cell at one time, paging in an entire LA is still a large waste of resources.
Additional proposals have been made to further narrow the initial paging area. One such proposal uses an initial paging area called a Neighbor Area (NA). In this solution, a neighbor list is stored for each cell (i.e., a list of cells adjacent to each cell). When an MS registers, the CellID is used to identify a neighbor list which then defines the NA for the first page attempt. If the MS is not located in the NA, the search is then widened to the LA, the PA, and the SA.
All of the prior art systems and methods for paging, however, still suffer serious disadvantages. First, these methods are implemented network wide, and do not take into account the varying sizes and geographies of the cells or the varying degrees of mobility of the subscribers in different areas. For example, while it may be efficient to search in the NA surrounding a large macrocell, it may not be appropriate to search in the NA of a microcell that is surrounded by other microcells because the area is too small, and the probability of finding the MS there is too low. Likewise, it may be efficient to search in the NA of a cell located in a downtown area where subscribers are generally slow moving, but it may not be appropriate along a highway.
A second disadvantage with the prior art methods is that they are implemented in a static manner. They do not take into account dynamic changes in the network and in subscriber behavior that may negatively impact the effectiveness of a static paging methodology.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a self-configurable paging system and method for a cellular telecommunications network that automatically adjusts the size of a paging area on a per-cell basis. The present invention provides such a system and method.
In one aspect, the present invention is a method in a cellular telecommunications network of automatically adjusting the size of a paging area on a per-cell basis. The method includes the steps of selecting an initial set of cells to utilize for a particular cell""s paging area; determining a paging efficiency for a plurality of paging attempts within the initial set of cells; and automatically adjusting the number of cells in the particular cell""s paging area if the paging efficiency falls outside an acceptable range.
In another aspect, the present invention is a method in a cellular telecommunications network of efficiently paging for mobile stations that last registered in a particular cell. The method begins by storing in a database, a plurality of sets of cells surrounding the particular cell. The sets of cells contain varying numbers of surrounding cells, and a first set of cells is selected to utilize for the particular cell""s initial paging area. This is followed by performing a plurality of paging attempts for mobile stations that last registered in the particular cell, and compiling statistics regarding how many of the plurality of paging attempts were successful at locating mobile stations within the first set of cells. If the statistics indicate that fewer paging attempts were successful than desired, the method selects a set of cells having a greater number of cells than the first set of cells. If, however, the statistics indicate that the paging efficiency was higher than desired using the first set of cells, the method selects a set of cells having a lesser number of cells than the first set of cells only if the predicted success rate for this set of cells would still be acceptable.
In yet another aspect, the present invention is a system in a cellular telecommunications network for efficiently paging for mobile stations that last registered in a particular cell. The system includes a database for storing a plurality of sets of cells surrounding the particular cell that contain varying numbers of surrounding cells. The system also includes a paging controller for selecting a first set of cells to utilize for the particular cell""s initial paging area, and for automatically adjusting the number of cells in the particular cell""s paging area if the number of successful page attempts/paging efficiency falls outside an acceptable range. Paging resources such as paging channels are used to perform a plurality of paging attempts for mobile stations that last registered in the particular cell. A statistical processor compiles statistics regarding how many of the plurality of paging attempts were successful at locating mobile stations within the first set of cells, the statistics being utilized by the paging controller to automatically adjusting the number of cells in the particular cell""s initial paging area.